Esophageal Imaging

Technical Aspects

Imaging

Imaging of the esophagus is challenging because of the location surrounded by many vital organs and poor distensibility of the esophagus. However, recent advancements of multidetector computed tomography (MDCT) and workstation and postprocessing techniques have amplified clinical application of computed tomography (CT) in the evaluation of esophageal diseases. These techniques enable coverage of a large volume in a very short scan time. Single breath-hold acquisition with thin collimation and isotropic voxels allows imaging of the entire esophagus with high-quality multiplanar reformation (MPR) and three-dimensional reconstruction. Generally, on CT, the esophagus appears as a well-delineated circular or oval shape of soft-tissue with a thin wall, which is less than 3 mm in a dilated esophagus, but can be thicker in a contracted esophagus. Thus, proper distention of the esophagus (by oral administration of effervescent granules and water) and optimal timing of administration of intravenous contrast material are necessary to detect and characterize esophageal diseases. Compared to endoscopy and double-contrast examination, CT esophagography can provide information on the esophageal wall and the extramural extent of disease. Specifically, MDCT plays a robust role in preoperative staging of esophageal malignant neoplasms. Furthermore, various benign conditions of the esophagus, including rupture, achalasia, esophagitis, diverticula, and varices can be visualized and detected in MDCT.

Magnetic resonance imaging (MRI) for esophageal imaging has been technically challenging because of the deep location of the esophagus and the degree of movement related to cardiac motion, peristalsis, and respiration, combined with the relatively slow acquisition time of MRI, which affect image quality. However, recent MRI technology has improved the achievable signal-to-noise ratio, and provides detailed information of the esophagus and the posterior mediastinum with high spatial resolution. High-resolution T2-weighted fast spin echo technique with phased array surface coil can visualize the individual components of the esophageal wall. Cine MRI technique, which can visualize peristalsis of the esophagus, can help staging of esophageal cancer, because interruption of peristalsis reflects impaired muscle function caused by stage T3 or T4 esophageal cancer.

Pathologic Conditions

Esophageal tumors include various types of pathologic conditions. We summarized esophageal tumors in Box 18-1 , classifying them into mucosal and submucosal tumors, because these differences closely associate with imaging features of the tumors. For example, typical submucosal tumors appear as a mass with smooth margins on CT and double-contrast examination. Benign esophageal tumors are not common, but sometimes it is difficult to differentiate benign from malignant tumors. Given the high mortality of esophageal cancer, pretreatment diagnosis for esophageal tumors is quite important.